Aprepitant of Formula I is a substance P/neurokinin 1 (NK1) receptor antagonist, chemically described as 5-[[(2R,3S)-2-[(1R)-[3,5-bis(trifluoromethyl)phenyl]ethoxy]-3-(4-fluorophenyl)-4-morpholinyl]methyl]-1,2-dihydro-3H-1,2,4-triazol-3-one and in combination with other antiemetic agents, is indicated for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of highly emetogenic cancer chemotherapy including high-dose cisplatin and prevention of nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy. Aprepitant is also indicated for the prevention of postoperative nausea and vomiting.

U.S. Pat. No. 5,719,147 provides a process for the preparation of aprepitant in a mixture of Form I and Form II which involves dissolving crude aprepitant in hot methanol, adding charcoal, then filtering, and washing the charcoal with hot methanol, cooling the methanol solution to room temperature, and then adding water drop wise. After being stirred at room temperature for 2 hours, the suspension is filtered to isolate the purified product as a white crystalline compound. The present inventors found that the XRD obtained by this process did not show consistency in the ratio of the mixture of Form I and Form II.
U.S. Pat. Nos. 6,096,742 and 6,583,142 provides crystalline Form I and Form II of aprepitant, process for making these forms, pharmaceutical compositions comprising them and their method of use. These patents specifically claim aprepitant Form I, which is substantially free of Form II, and Form II which is substantially free of Form I of aprepitant.
Anal. Chem. (2003) 75:605-611, provides characterization and quantization of aprepitant polymorphs by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy.
Several processes have been reported for the preparation of aprepitant and various polymorphic forms for example in PCT Publication Nos. WO 2007/016582; WO 2007/039883; WO 2007/044829; WO 2007/088483; WO 2007/112457; WO 2007/147160; WO 2008/026216; WO 2008/044102; WO 2008/104512; WO 2009/001203.
There is a continuing interest in morphological forms among other properties. There is a need in the art for a process for producing crystalline aprepitant having Form I content in a consistent range. Extensive laboratory and full scale research has resulted a process for the preparation of crystalline aprepitant having not more than 15% by weight of Form I content, which is stable over the time and is suitable for formulating aprepitant.